IgG antibodies against viruses

I have elevated IgG antibodies against the measles virus. Doctors always told me that's because of the MMR vaccine i received and simply meaning i'm immune to new infections with the virus.
Recently i read an article which i unfortunately can't recall explaining that IgG is often misinterpreted and does not always mean a person is "immune".

Besides having an elevated IgG against measles i also have lymphoid nodular hyperplasia in the ileum (small intestine). Dr. Andrew Wakefield found a connection between the measles virus from the MMR vaccine, autism/encelopathy/brain disorders and ileal nodular lymphoid hyperplasia. Although i'm not sure if his research is credible because the publications have been retracted.

Then just a few minutes ago i read something about "Subacute sclerosing panencephalitis". It's encephalitis caused by the measles virus. Unfortunately i match most of the symptoms.
Might this just be a part of the puzzle that's making me so ill? Should i follow up on these findings?